1. Field of the Invention
The present invention relates to an electrophotographic copying machine and, more specifically, to a copying machine capable of so-called editing function, capable of reproducing only a specified area in document.
2. Discussion of the Background
There has been proposed an electrophotographic copying machine capable of copying only a specified area in a document on a copying paper, namely, a copying machine, for example U.S. Pat. No. 4,582,417 (Yagasaki et al.), capable of so-called editing function, which scans a document optically to form an electrostatic latent image on a photosensitive member, develops the electrostatic latent image with a toner, transfers the toner image to a copying paper, and fixes the toner image on the copying paper.
Such a conventional electrostatic copying machine is based on a principle of omitting the reproduction of an undesired area in a document by erasing electric charge in an area on the photosensitive member corresponding to the undesired area in a document prior to developing the electrostatic latent image so that the development of the electrostatic latent image of the undesired area is impossible.
It is one of the methods of specifying a certain area not to be copied or a certain area to be copied employed in such a copying machine capable of editing function to give orthogonal coordinates data, namely, numerical data, representing the certain area.
For example, when the certain area is a single rectangular area as illustrated in FIG. 8, the area is specified by giving the x-coordinates A and B, and the y-coordinates C and D of one end a (A,C) and the other end d (B,D) of a diagonal, or one end b (A,D) and the other end c (B,C) of the other diagonal. In the following description, it is assumed in FIG. 8 that the upper right-hand corner is the origin (0,0), positive values for X are measured to the left on the x-axis extending leftward, positive values for y are measured downward on the y-axis extending downward, and a copying paper is moved in the negative direction of the x-axis, namely rightward in FIG. 8.
Incidentally, the method of specifying an area by giving the x-coordinates A and B, and the y-coordinates C and D has a problem that an operator is liable to err in the order of input in giving the coordinates data.
Generally, the operator recognizes visually, namely, two-dimensionally, the area defined by four points a, b, c and d shown in FIG. 8. Accordingly, the operator pays attention to the x-coordinates A and B, and the y-coordinates C and D, however, the operator, in general, does not pay attention to the order of input of the coordinates data. Therefore, in some cases, x-coordinate data is given in the order of B and A, and y-coordinate data is given in the order of D and C. A CPU incorporated into the copying machine controls the timing of edit-copying operation matching with the movement of the copying paper. Accordingly, if the order of input of the coordinates data is wrong, the CPU is unable to specify the area, and hence edit-copying operation is impossible.
It is sometimes found when the area specified by giving data with a numeric keyboard is copied that the area of copied image is slightly different from the requested area. In such a case, according to Yagasaki et al., the operator must regive the four data with the numeric keyboard. Virtually this is very inconvenient.